In the railway art railway trucks are provided with wheelsets which engage laterally spaced rails that are disposed at a predetermined gage or lateral spacing, measured as the distance between confronting gage surfaces on the inner sides of the rail heads of the respective rails. It is well known that the application of lubricant to the gage surface of one or both rails can significantly reduce friction and wear between the rail gage surfaces and the flanges of the truck wheelsets running on the rails without adversely affecting the friction between the mutually engaged surfaces of the wheel tread surfaces and the rail head running surface, which is required to drive a train.
It has been suggested that proper rail gage surface lubrication can provide significant operating cost savings through fuel cost savings and through extended rail and wheel service life. In order to provide gage surface lubrication, onboard (e.g. carried by a locomotive or special vehicle) and way-side lubrication systems are commonly used. The reader is referred to the art which includes detailed description of a variety of such lubrication systems as further detailed description thereof here is believed to be unnecessary for an understanding of the present invention by one skilled in the art.
Problems have arisen in the use of known gage surface lubrication systems as a result of difficulties encountered in the control of lubricant distribution. Generally, lubricant is distributed along the gage surface of a rail by the passing wheelsets of the rail car trucks. The lubricant is applied to the wheel flange surface which confronts the rail head gage surface, and is distributed by a wiping action along the rail gage surface as a result of the rolling movement of the wheel along the rail. It is important that lubricant be distributed as uniformly as possible along the rail head gage surfaces from the confronting wheel flange surfaces with a minimal spread (or lateral migration) of lubricant to the rail head running surface. However, the rolling motion of truck wheelsets along the rails is always accompanied by lateral movement of the wheel flanges between the rail gage surfaces. This lateral movement is a significant factor in causing lubricant to migrate toward the rail running surface.
Contamination of the rail running surface with lubricant introduces numerous problems, including increased difficulty of detecting rail flaws and higher L/V ratios with resultant increased potential for rail climbing by guiding wheel flanges on both freight car and locomotive trucks. Excessive lubricant application leads to accumulation of lubricant on the rail running surface as well as on truck and car body surfaces, resulting in reduced effectiveness of friction groups and resilient side bearings, reduced maximum traction and braking forces which can be extremely hazardous for train operations, and impaired electrical conductivity between the rails and wheels. While lubricant on the rail running surface reduces rail wear it thereby also increases the possibility of rail head metal fatigue and the subsequent development of transverse fatigue cracks in the rail head surface and gross rail failure.
The inherent side-to-side oscillation of typically coned rail car wheelsets on the rails will inevitably cause some lateral migration of lubricant onto the rail head running surface. This effect is aggravated on worn wheel and rail head interfaces due to closer matching of the contacting surface portions of the wheel flange and rail gage surfaces. Problems with lubricant migration can be further exacerbated by misalignment of lubricant applicators on the lubricant distributing wheelsets, which results in lubricant being applied nearer the flange throat and wheel-rail running surfaces area than desired.